For variegated engineering applications, e.g. in the precision mechanics and electronic industries, guide means are required for exact translatory movements. A very simple device consists of a shaft which is seated on a support and which, in turn, rides an open ball bush that may comprise a top plate for supporting an apparatus. However, this type of guide is not in itself locked, or lockable, against rotation.
In FR-A-1 124 901, a rail was proposed whose head carries on either side pairs of shafts opposite to which a carriage has further shaft pairs of like sort; a plurality of balls between adjacent shaft pairs is provided for smooth run of the carriage. But the design expenditure is large since continuous series of balls must be held or restrained along the entire rail. Similar to CH-A-347 049, the two shafts are fixed partly in a broad rectangular groove merely by the heads of a few bolts located in side flanges so that, especially under load, parallelism is not warranted at all.
Other guide systems such as disclosed in DE-A-3 040 711 and EP-B-0 080 515 make use of two shafts supported on single blocks or by clamping profiles that restrain the shafts throughout their length, tight fit being an absolute necessity for accurately guiding a carriage whose rollers or linear ball bearings ride on the shafts. Their outer shaft peripheries may be grasped and possibly forced inwards by a pressure plate. It is critical, though, to what extent the fixing screws or bolts are tightened, as a deformation of the shafts may easily occur.
In accordance with EP-B-0 245 656, adapter pieces are used for fixing shafts in a rail body designed as an integral clamping profile. While the attachment components do not influence the force which clamps the shafts in their position, there is no bolting of them so that exact parallelism is not safeguarded. The same applies to a so-called roller guide unit comprising shafts rolled down into grooves of a support.